'The Big Bang Theory' Season 4, Episode 11 Recap (VIDEO)

After skirting the issue for most of the season, 'The Big Bang Theory' finally returned to its emotional center -- Leonard and Penny. The two didn't rekindle their relationship, but we got the strongest evidence so far that feelings still exist between them and that a future reunion is a distinct possibility.

The gang dressed up as the Justice League of America to compete in a New Year's costume party contest at the comic book store. Zack, Penny's ex-boyfriend, returned and had some of the funniest, most lovably doltish, lines of the episode. Take, for example, the scene where Penny and Zack delivered a copy of 'Science' magazine to Leonard:

Zack: "Check it out. All about planets this month."
Leonard: "That's an atom."
Zack: "Agree to disagree. That's what I love about science. There's no one right answer."

The episode was chock full of funny bits, making it the most satisfying this season so far. One of the best moments took place while Leonard, dressed as the Green Lantern, read his copy of 'Science' with glasses over his mask. Meanwhile, Sheldon, dressed as the Flash, ran back and forth across the apartment. Sheldon: "We're going to be late. I'm pacing nervously." Leonard: "You're jogging." Sheldon: "This is how the Flash paces." And Sheldon's imagined dash to the Grand Canyon to express frustration over Leonard was the biggest laugh-out-loud moment in recent memory.

Zack was roped in to the costume contest dressed as -- what else? -- a buff Superman, replacing Leonard in the role. Penny reluctantly agreed to dress as Wonder Woman, but bowed out after being pressured by Zack. After Leonard gave her a pep talk, he discovered, no doubt to his relief, that she and Zack weren't really dating. Instead, Penny simply didn't want to be alone on New Year's Eve.

Still, that information didn't help Leonard's jealousy as Penny and Zack shared a New Year's kiss. But Penny's embarrassed and slightly guilty glance at Leonard afterward spoke volumes. Will the two ever get back together? It seems a forgone conclusion at this point. But, unfortunately, fans will have to wait several weeks until after the holiday hiatus for further developments.

Other Funny Moments:
Wolowitz and Raj argue that they didn't bully Zack: Wolowitz: "I know bullying. He left here unswirlyed and his ass crack was underpants-free." Raj: "And nobody drew a penis on his forehead."

Sheldon suggested Leonard apologize to Zack with a Milk Dud: "Milk Duds, with their self-deprecating name and remarkably mild flavor, are the most apologetic of the boxed candies."

Zack told the gang he hadn't been to a comic book store in quite some time: "I haven't been to a comic book store in, literally, a million years." Sheldon: "Literally? Literally, a million years?"

Raj complained about having to dress as Aquaman: "I don't want to be Aquaman! He sucks underwater! He sucks fish pee!" Sheldon: "Excuse me. I believe Aquaman uses his telepathic powers to request the fish do their business elsewhere."

Wolowitz explained that Bernadette wasn't available to dress as Wonder Woman on New Year's Eve: "She and her lab team are under quarantine. Seems at the Christmas party they were doing Jello shots out of petri dishes that used to contain Yellow Fever."

Sheldon recommended alternate costume choices after Penny refused to dress as Woman Woman: "Obviously, we're no longer a justice league. We have no choice but to switch to our Muppet Baby costumes."